Previous studies have demonstrated a role for angiotensin II (AngII) and myofibroblasts (myoFb) in cardiac fibrosis. However, the role of PKC-delta in AngII mediated cardiac fibrosis is unclear. Therefore, the present study was designed to investigate the role of PKC-8 in AngII induced cardiac collagen expression and fibrosis. AngII treatment significantly (p < 0.05) increased myoFb collagen expression, whereas PKC-delta siRNA treatment or rottlerin, a PKC-8 inhibitor abrogated (p < 0.05) AngII induced collagen expression. Myo-Fb transfected with PKC-delta over expression vector showed significant increase (p < 0.05) in the collagen expression as compared to control. Two weeks of chronic AngII infused rats showed significant (p < 0.05) increase in collagen expression compared to sham operated rats. This increase in cardiac collagen expression was abrogated by rottlerin treatment. In conclusion, both in vitro and in vivo data strongly suggest a role for PKC-delta in AngII induced cardiac fibrosis. (C) Elsevier Inc. All rights reserved.